Ocean, tidal and stream hydrokinetic energy is one of ten tracks being offered at HydroVision International 2010. Experts will discuss the status of this fledgling sector and the pathway to commercial production.

By Roger Bedard

The idea of harnessing the vast power of Earth's oceans has fascinated and tantalized humans for centuries. Today, we may be on the cusp of realizing this potential.

Ocean, tidal and stream energy are renewable resources that we should seriously consider as an addition to our global portfolio of energy supply alternatives. Here's why:

– The wave and tidal/stream hydrokinetic energy resource available to be converted to electricity is significant;– The technology to convert those resources to electricity is emerging and is ready for testing in natural waters;– Wave and tidal/stream hydrokinetic energy can be cost competitive with other renewable technologies; and– We can overcome the significant challenges that remain to finding the pathway to commercialization of wave and tidal/stream energy technologies.

The conversion of ocean wave energy, in-stream tidal, open-ocean and river currents into electricity will be the subject of much discussion at HydroVision International 2010, July 27-30, in Charlotte, N.C. It should not be confused with conventional hydro using a dam, impoundment or diversionary structure.

A robust electricity system of the future will be a balanced and diversified portfolio of energy supply alternatives. Our oceans are a public resource held in trust and accommodating multiple users. Fishermen make their living from the ocean and commercial ships navigate the oceans to deliver goods. Recreational boaters, surfers and those who just walk on the beach enjoy the ocean, while whales and other aquatic life make the ocean their home. Ocean energy could be one of those users working in harmony with other users and providing renewable energy for the overall good of our society.

The advantages of ocean energy are numerous. Studies have indicated that the high power density (kW/m2 for currents and kW/m of wave crest length for wave) of the resource results in smaller energy conversion machines lower in capital cost than other renewable technologies. The remoteness and hostility of the ocean environment, however, can result in higher deployment, operation and maintenance costs. But on balance, the cost of electricity can be comparable or lower than power produced by other renewable technologies.

Other benefits include: Providing a new, relatively environmentally benign, renewable source for meeting load growth and renewable portfolio goals; easy assimilation into the grid (because of the predictability of the resource); easing transmission constraints (since a large percentage of the world's population lives near a coast) with minimal, if any, aesthetic concerns; reducing dependence on imported energy supplies and increasing energy security; lowering the risk of future fossil fuel price volatility; reducing emissions of greenhouse gases compared with fossil fuel-based generation; and stimulating job creation and economic development by using an indigenous resource.

A large number of small companies backed by government, private industry, utilities, and venture capital are leading the commercialization of technologies to generate electricity from ocean wave and tidal/open-ocean in-stream energy resources. Industries such as ship building are looking for opportunities to diversify, grow, and compete. These industries provide a trained workforce and institutional knowledge that will benefit ocean renewable energy technologies while helping to re-vitalize their own sectors.

The economic opportunities are significant. A relatively minor investment in research, development and demonstration could create a global industry generating billions of dollars of economic output and the employment of thousands.

The Pelamis unit, developed by Pelamis Wave Power, is a linear absorber. The four sections of this linear absorber move relative to each other, and this motion is converted at each hinge point into electricity by a hydraulic power converter system.

The European Union, Australia, and New Zealand are leading the development and commercialization of these technologies through:

– Supporting the technology developers with funding.– Funding subscale and full scale test facilities. – Establishing goals for com-mercialization.– Developing roadmaps that point out the pathways to meet these goals.– Providing financial incentives necessary to meet those goals.

Other nations are starting to get involved. Canada, for example, is implementing a tidal pilot demonstration project in the Minas Passage. This project is now funded at tens of millions of dollars and the first of three large scale (1 MW class) machines has been deployed. Two other tidal machines as well as the submerged transmission cable will be deployed in 2011.

The U.S. Department of Energy manages a Waterpower Research, Development and Demonstration (RD&D) program, which began in fiscal 2008 at $10 million, increased to $40 million in fiscal 2009 and rose again to $50 million in fiscal 2010. The term "Waterpower" encompasses conventional hydro and the emerging Wave/Tidal/Stream technologies as well as ocean thermal energy conversion.

Today, there are a variety of ocean/tidal/stream energy conversion technologies at various stages of development. Several dozen devices have progressed to rigorous subscale laboratory wave-tank or tow-tank model testing. About two dozen have advanced to short-term tests in natural waters. And only a few devices have progressed to long-term testing of full-scale prototypes in natural waters. The time period needed for these technologies to progress from concept to deployment is five to ten years. It is too early to know which technologies will turn out to be the most cost-effective, reliable, and environmentally sound, and the desired technology may differ by location.

There is uncertainty as to whether large scale deployment of ocean/tidal/stream technologies can be done in an environmentally acceptable way. Project developers, environmental entities, utilities and governments are addressing the environmental issues associated with getting ocean/tidal/stream machines in the water. Research conducted to date indicates that environmental impacts from many of these emerging technologies are minimal. However, regulators and the public insist that minimal impacts be demonstrated before proceeding. A gradual scale-up of deployments, following a carefully designed, adaptively managed approach is likely the only way such demands can be satisfied in a sensible way.

The PowerBuoy, from Ocean Power Technology, is an example of a point absorber. These devices absorb wave energy from all directions.

It is critical for the success of this industry to gain a full understanding of all life cycle-related issues over the coming years to pave the way for larger scale commercial deployments. Such understanding can only be gained in a practical way from the deployment of prototype and pilot demonstration systems in the ocean. Successful deployment of prototype and pilot demonstration systems will not only address technology and economic related issues, but will also provide confidence to regulators, the general public and investors. Both market push (RD&D and portfolio standards) and market pull mechanisms (economic incentives to encourage deployment) will be required to successfully move this technology sector forward and develop the capacity to harness energy from the ocean.

It is very unlikely that any of this early stage development will be funded by the private sector because the risk of failure is too high. When a technology developer can test a prototype that shows promising performance, reliability and cost, then the private sector investors may be interested. Even at that point, the private sector will not want to assume all of the financial risk and exposure to fully fund the first demonstration projects, or the first commercial projects. Some sort of support for these early commercial projects will be essential to get the industry started.

The eventual level of ocean/tidal/stream power capacity to be deployed will be strongly dependent on enabling actions and policies that support the development of the industry. The establishment of deployment and timeline goals and the RD&D pathways to success are needed to fully develop the potential of this industry. Given the long lead times inherent in capital intensive industries like energy, investment and policy decisions cannot be delayed without risk of losing opportunities for technology options that we expect will prove tremendously valuable in a carbon-constrained future.

Come to the Ocean/Tidal/Stream Power track at HydroVision International 2010 and learn how developers and early adopters are moving down the path to commercialization of Ocean/Tidal/Stream technologies.

A Focus on Ocean/Tidal/Stream Power at HydroVision International 2010

One of 10 concurrent conference tracks at HydroVision International 2010 will focus on Ocean/Tidal/Stream Power. Sessions in the track include: Siting Considerations; Environmental Status; Standards and Resource Assessments; and Testing Centers and Project Opportunities. To learn more about HydroVision, go to www.hydroevent.com.

Roger Bedard is Ocean Energy Leader in the Renewable program area of the Generation Sector at Electric Power Research Institute (EPRI). He is the track co-chair for the Ocean/Tidal/Stream Power track at HydroVision International, to be held July 27-30, 2010 in Charlotte, N.C.